Your tale is not that uncommon as of late. In the JavaScript-land, Babel (a transpiler) moved to Phabricator some time ago and others like eslint have been considering doing the same for the same exact reasons you have stated. Solving bad contributions (be it issues or anything else) take too much time, so we must get rid of the bad contributors. In my humble opinion this is like solving the immigration issues of the US by building even bigger and bigger walls until you don’t seem to have the problem anymore, a Trumpism.

Kindness is a good starting point (with pretty much everything in life) but it obviously isn’t always enough. You got two options: make the initial entry as hard as possible to scare away those contributions that seem unwanted or actually try and solve the issues behind the issue in front. You are getting overwhelmed by bad contributions: is it because the contributions are just so bad that you can’t handle them or is there simply too few people to handle them?

Have you read Healthy Open Source by @mikeal which outlines how NodeJS handles it’s contributor ecosystem by being an open open source project where those who make (significant) contributions (to some areas of the code or otherwise) are invited to join to collaborate. The sheer amount of people that collaborate towards a common goal can definitely alleviate or completely remove the problems of having some bad issues every once in while. 100 bad issues per day is nothing when you have 100 enthusiasts looking at them. Having 100 bad issues per day when you are the only one solving them is a suicide mission.

In the eslint-thread Nicholas C. Zakas made a point about not getting any responses for a roll call of community members to help out. There has been some responses to the said issue since then but (again in my humble opinion) was that the roll call wasn’t for contributors: it was for computer janitors and cleaners. Obviously janitors and cleaners are needed in the real world, but the amount of people that aspire to be the best community manager in the world are far and in-between, especially when talking about open source software.